Jednoduchý prohlížeč bmp. Upload kvůli hledání bugu.

bmview.c

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <SDL/SDL.h>
#include <SDL/SDL_gfxPrimitives.h>

#define WIDTH 800
#define HEIGHT 600
#define RED 0xff0000ff
#define BMP_TYPE 19778

typedef struct {
  unsigned short type;
  unsigned long size;
  unsigned short reversed1;
  unsigned short reversed2;
  unsigned long offsetbits;
}__attribute__((packed)) BITMAPFILEHEADER;
typedef struct {
  unsigned long size;
  unsigned long width;
  unsigned long height;
  unsigned short planes;
  unsigned short bitcount;
  unsigned long compression;
  unsigned long sizeimage;
  long xpelspermeter;
  long ypelspermeter;
  unsigned long colorsused;
  unsigned long colorsimportant;
}__attribute__((packed)) BITMAPINFOHEADER;
typedef struct {
  unsigned char blue;
  unsigned char green;
  unsigned char red;
  unsigned char offset;
}__attribute__((packed)) SINGLE_PIXEL;

void printHelp(char *name);

void displayWarning(SDL_Surface *screen);

int main(int argc, char *argv[])
{
  if (argc != 2) {
    printHelp(argv[0]);
    return 1;
  }

  if (SDL_Init(SDL_INIT_VIDEO) < 0) {
    fprintf(stderr, "Error: cannot load SDL: %s\n", SDL_GetError());
    return 1;
  }

  atexit(SDL_Quit);

  int good_picture = 0;
  unsigned int width = WIDTH, height = HEIGHT;
  int pixels_per_color = 0;
  int colors = 16;
  int compression = 0;
  unsigned long size = 0;
  unsigned long numColors;
  
  BITMAPFILEHEADER bmfh;
  BITMAPINFOHEADER bmih;
  SINGLE_PIXEL *cplt;
  unsigned char *pixels;

  FILE* picture = fopen(argv[1],"rb");

  if (picture != NULL) {
    if (fread(&bmfh,sizeof(BITMAPFILEHEADER),1,picture) == 1) {
      if (bmfh.type == BMP_TYPE) {
	if (fread(&bmih,sizeof(BITMAPINFOHEADER),1,picture) == 1) {
	  width = bmih.width;
	  height = bmih.height;
	  pixels_per_color = bmih.bitcount;
	  compression = bmih.compression;
	  
	  printf("width: %d\n",width);
	  printf("height: %d\n",height);
	  printf("bitcount: %d\n",pixels_per_color);
	  if (pixels_per_color < 24) {
	    numColors = 1 << pixels_per_color;
	    printf("numColors: %lu\n",numColors);

	    if (pixels_per_color == 8) {
	      cplt = malloc(sizeof(SINGLE_PIXEL)*numColors);
	      if (cplt == NULL) {
		fprintf(stderr,"Error: can't allocate memory.\n");
		fclose(picture);
		return 1;
	      }
	      if (numColors != fread(cplt,sizeof(SINGLE_PIXEL),numColors,picture)) {
		fprintf(stderr,"Error: can't read color palette.\n");
		fclose(picture);
		free(cplt);
		return 1;
	      }
	    }
	  }
	  size = bmfh.size - bmfh.offsetbits;
	  printf("Size of image: %lu\n",size);

	  pixels = malloc(size*sizeof(unsigned char));
	  if (pixels == NULL) {
	    fprintf(stderr, "Error: can't allocate memory.\n");
	    free(cplt);
	    fclose(picture);
	    return 1;
	  }
	  if (size != fread(pixels,sizeof(unsigned char),size,picture)) {
	    fprintf(stderr,"Error: can't read input file.\n");
	    free(cplt);
	    free(pixels);
	    fclose(picture);
	    return 1;
	  }
	  good_picture = 1;
	}
      }
    }
    fclose(picture);
  }

  unsigned int nejbliz_nas = width;
  while (nejbliz_nas % 4) nejbliz_nas++;
  printf("nejbliz: %d\n",nejbliz_nas);

  SDL_Surface *screen = SDL_SetVideoMode(width,height,colors,SDL_HWSURFACE|SDL_DOUBLEBUF);

  int done = 1;
  int barva = 0;
  int invertovat = 0;

  while (done) {
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
      switch (event.type) {
      case SDL_QUIT:
	done = 0;
	break;
      case SDL_KEYDOWN:
	if (event.key.keysym.sym == SDLK_ESCAPE)
	  done = 0;
	if (event.key.keysym.sym == SDLK_UP)
	  barva += 5;
	if (event.key.keysym.sym == SDLK_DOWN)
	  barva -= 5;
	if (event.key.keysym.sym == SDLK_i) {
	  if (invertovat) invertovat = 0;
	  else invertovat = 1;
	}
	break;
      }
    }

    if (!good_picture) {
      displayWarning(screen);
    } else {
      for (unsigned int i = 0; i<size; i++) {
	if ((i%nejbliz_nas) >= width) {
	  continue;
	}
	  
      	int pix_r = cplt[pixels[i]].red;
      	int pix_g = cplt[pixels[i]].green;
      	int pix_b = cplt[pixels[i]].blue;
	
      	if ((pix_r + barva) < 0) pix_r = 0;
      	else if ((pix_r + barva) > 0xff) pix_r = 0xff;
      	else pix_r = pix_r + barva;
	
      	if ((pix_g + barva) < 0) pix_g = 0;
      	else if ((pix_g + barva) > 0xff) pix_g = 0xff;
      	else pix_g = pix_g + barva;
	
      	if ((pix_b + barva) < 0) pix_b = 0;
      	else if ((pix_b + barva) > 0xff) pix_b = 0xff;
      	else pix_b = pix_b + barva;
      	if (invertovat) {
      	  pix_r = 0xff - pix_r;
      	  pix_g = 0xff - pix_g;
      	  pix_b = 0xff - pix_b;
      	}
      	unsigned int clr = pix_r*0x1000000 + pix_g*0x10000 + pix_b*0x100 + 0xff;
      	pixelColor(screen,i%nejbliz_nas,height-i/height-1,clr);
      }
      /* for (int j=0; j<width; j++) { */
      /* 	for (unsigned int i=0; i<numColors; i++) { */
      /* 	  unsigned int clr = cplt[i].red*0x1000000 + cplt[i].green*0x10000 + cplt[i].blue*0x100 + 0xff; */
      /* 	  pixelColor(screen,2*i,j,clr); */
      /* 	  pixelColor(screen,2*i+1,j,clr); */
      /* 	} */
      /* } */
      SDL_Flip(screen);
    }
    SDL_Delay(10);
  }

  if (pixels != NULL) free(pixels);
  if (cplt != NULL) free(cplt);
  
  return 0;
}

void printHelp(char *name)
{
  printf("bmpview\n\nusage:\n");
  printf("%s file\nwhere: file is input *.bmp file\n",name);
}

void displayWarning(SDL_Surface *screen)
{
  stringColor(screen, 5, 5, "Error: cannot read or file doesn't exist.", RED);
  SDL_UpdateRect(screen, 0,0,0,0);
}